Different types of projection lighting systems are known and used in various illumination applications. Typical applications include video projectors, display lighting, automotive lighting and scientific instrumentation.
Ultra high-pressure mercury lamps, metal-halide lamps, xenon lamps, halogen lamps and lasers are examples of conventional types of light sources that are used in projection lighting systems. In recent years, the development of SSL technology has led to attempts to construct projection systems which use different types of light-emitting diodes. Compared with conventional light sources, SSL light sources have a wider range of color gamut, higher color saturation and a smaller line width. SSL light sources also have a long life time and are mercury-free. An example of a lighting arrangement using SSL light sources is disclosed in US 2013/0021822 A1. The disclosure relates to an optical waveguide plate.
The required light source characteristics depend on the application. Video projectors, for example, require small blue, red and green high-intensity light sources which emit light with a small etendue. It is possible to improve existing SSL lighting devices in these respects.